The female is larger than the male with slightly different markings, has a paler colour and does not have feathered antennae (unlike the male). Northern or upland examples are more intensely coloured, with the female bluish-grey. The adult females fly at night when they occasionally come to light, usually early in the night.

They overwinter as pupae within a light brown, papery pear-shaped cocoon, with a closed circle of upward pointing spines around the opening. It is attached to a plant stem near the ground. Eggs are laid from April to May in batches attached to the foodplant. The caterpillars can be found from late May to August.

Flight Season

Flies in late March through to April and May, in one generation.

Size and Family

  • Family Emperors (Saturniids)
  • Large Sized
  • Wingspan Range 55-80mm

Conservation Status

  • UK BAP: Not listed
  • Common

Caterpillar Food Plants

Heathers, Meadowsweet (Filipendula ulmaria), Alder Blackthorn (Frangula alnus), Bramble (Rubus fruiticosus), Hawthorn (Crataegus monogyna) Blackthorn (Prunus spinosa), sallows (Salix spp.) and birches (Betula spp.).


Heathland, moorland bogs, fens, hedgerows, field margins, woodland ridges, mature sand dunes and other scrubby places.


  • Countries – England, Wales, Scotland, Ireland
  • Widely distributed in most parts of mainland Britain, the Channel islands, Isle of Man, Orkney, Hebrides and Ireland.
  • Distribution Trend Since 1970’s = Britain: Suspected stable


Emperor moth (male) - Adam Gor

Emperor moth (male)

Emperor moth (male/underwing) - Adam Gor

Emperor moth (male/underwing)

Emperor moth (female) - Adam Gor

Emperor moth (female)

Emperor moth (female /underwing) - Bob Eade

Emperor moth (female /underwing)

Emperor moth (female & male) - Bob Eade

Emperor moth (female & male)

Emperor moth (eggs/young caterpillars) - Dean Morley

Emperor moth (eggs/young caterpillars)

Emperor moth (caterpillar) - Tapio Kujala

Emperor moth (caterpillar)

Emperor moth (pupa) - Ilia Ustyantsev

Emperor moth (pupa)